Bacterial vaginosis is a syndrome in which the normal Lactobacillus-predominant vaginal flora is replaced with mixed anaerobic-predominant organisms. It is present in 10 to 25% of women in the general population, and is the most common vaginal infection. It has been associated with a number of adverse sequelae in reproductive health including acquisition of HIV, pelvic inflammatory disease, cervical dysplasia, and complications of gynecological procedures. During pregnancy it has been associated with an increased risk of preterm birth and postpartum maternal infection. However, the vaginal microbial flora remains poorly understood. Information on variation in microbial flora and its association with BV from a longitudinal study is unavailable. This prospective observational study aims to advance our knowledge of the natural history and abnormal alteration in vaginal microbial flora, and to identify risk factors that are associated with these changes. A total of 3600 healthy, non-pregnant women of reproductive age have been enrolled and are being followed in Birmingham, Alabama for one year (baseline visit plus once every three months afterwards, totaling five visits). Detailed information on sociodemographic status, medical history, hygiene practice, sexual behavior and psychosocial stress were collected through in-person interviews. Routine gynecological and dental examinations were carried out during the study visits. Samples of vaginal secretion and blood were collected. Laboratory tests to quantify vaginal microbial flora and to identify infection of bacterial vaginosis as well as common sexually transmitted diseases were conducted. Sub-studies evaluate the day-to-day change in vaginal flora, and the effect of cessation of douching. The final study visits were completed in June 2003, and various analyses are underway. An abstract on the a pilot randomized trial of douching cessation and the incidence and persistence of bacterial vaginosis was presented at the Society for Gynecologic Investigation in 2004. Manuscripts describing the degree to which women with BV are asymptomatic, and the association between psychosicial stress and BV incidence were published in FY05, and a paper on contraceptive use and BV is under review. Abstracts describing the association between BV and periodontal disease was presented. Ongoing analysis are focusing on the effect of douching cessation and BV incidence, and dietary risk factors for BV.